US2957427A

US2957427A - Self-regulating pumping mechanism

Info

Publication number: US2957427A
Application number: US631239A
Authority: US
Inventors: Walter J O'connor
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-12-28
Filing date: 1956-12-28
Publication date: 1960-10-25
Anticipated expiration: 1977-10-25

Description

Oct. 25, 1960 w. J. O'CONNOR 2,957,427

T SELF-REGULATING PUMPING MECHANISM Filed Dec. 28, 1956 4 Sheets-Sheet 1 INVENTOR Walter J. O'Connor g Y 3W M Oct. 25, 1960 w. J. O'CONNOR 2,957,427

SELF-REGULATING PUMPING MECHANISM Filed Dec. 28, 1956 4 Sheets-Sheet 2 Oct. 25, 1960 w. .1. O'CONNOR SELF-REGULATING PUMPING MECHANISM 4 Sheets-Sheet 3 Filed Dec. 28, 1956 Walter J. O'Connor Oct. 25, 1960 w. J. OCONNOR 2,957,427

SELF-REGULATING PUMPING MECHANISM Filed Dec. 28. 1956 4 Sheets-Sheet 4 Fig .7.

INVENTOR. Walter J. O'Connor BY @XM; W

2,951,427 SELF-REGUIJAIING PUMPING MECHANISM Walter 'J. 'OConnor, 412 W. Washington Blvd, Grove City, Pa.

Filed Dec. 28, 1956, Ser. No. 631,239 Claims. (Cl. 103-420) This invention relates to new self-regulating pumping mechanism having rotor and stator pump elements which are relatively axially movable in response to pressures opposing the pumping action force for the regulation of the same. More particularly, this invention pertains to new mechanism utilizing helically threaded rotor and stator members with provision for relative axial movement therebetween so as to automatically and selectively regulate the pumping force.

In the pumping of slurries and viscous substances, for example, pressure relief is commonly provided, particularly when positive displacement pumps are used, to prevent the development of excessive pressure detrimental to the equipment being used, or to the operation being conducted. In the case of some'materials such as slurries containing abrasive particles, or in the case of viscose materials, or in the case of toxic substances, the use of valves such as pressure relief poppet valves has given rise to a number of difficulties. With high-solids content slurries, solids particles discharging through such a relief tend to prevent proper reseating; with viscous materials, the cleanliness of the surroundings about the discharge side of the relief valve has been a' problem; particularly in connection with food and health-material processing industries where cleanliness is indispensable; with toxic or corrosive materials, such pressure relief ventings have had to be provided for in a manner to safeguard men and equipment from the effects of material so discharged in the course ofsystem pressure relief. Difficulties and deficiencies of'prior practices may be overcome by utilization of my invention disclosed herein. Thus, in the event that greater than desired pressures tend to occur, mechanism embodying my invention provides for the relative axial movement of rotor and stator members in the 'pump element to automatically self-regulate the maximum pressure which can be developed by the pumping action in the system. In thatway, no pressure relief valve provision is needed in which the material undergoing processing needs to be dis charged from the system via any such pressure relief outlet. Moreover, with materials to be processed of a' character normally imposing a high-starting torque load upon a pump, my invention may be used, if desired, to initiate pumping action at a relatively lower starting torque until the mechanism attains such a speed for example as to enable it to handle the normal load involvedin such case. Rotor and stator parts for new mechanism and practices of my invention may have operative configurations for pumping action of the kind disclosed in expired Patents Nos. 1,892,217 and 2,028,407.

Other objects and advantages will be apparent from the following description and the accompanying drawings, which are illustrative only, in which I Figure 1 is a view in side elevation, partly in section, of one embodiment of my new self-regulating pumping mechanism;

I Figure 2 is a view in side elevation, partlyin section,

2,957,427 Patented Oct. 25, 1960 ice of the structure shown in Figure 1 with parts thereof having moved axially relative to one another for pressure regulating purposes;

Figure 3 is a plan view Figure 1;

Figure 4 is a view in longitudinal section through a further embodiment of my invention; Figure 5 is a view taken along line taken along line III-4H of V-V of Figure 4;

Figure 6 is a view in longitudinal section of a still further'embodiment of my invention; and

Figure 7 is a view of yetanother embodiment of'my invention.

Referring to Figures vice 10 is shown therein which may be employed in many industries which require pumping, inclusive without limitation, for example, of the fields of food processing, chemical compositions, frit and slip mixtures for the enameling and pottery, plasma and other medical supplies, pharmaceuticals, petroleum base materials, to men tion but some of the possibilities.

In device 10, a cabinet 11 may be supported on a plant floor by legs 12. A mixing receptacle 13 which may instead be only a feed hopper for the material which will undergo pumping action is also suitably affixed to cabinet 11. A post 14 is rigidly connected to cabinet 11 to in turn support one embodiment 15 of new mechanism of this invention.

Mechanism 15 may comprise a rigid frame 16 whichis secured to post 14. Frame 16 in turn is provided with. sleeves 17 fixed thereto for the receipt of guide rods 18, guide rods 18 being adapted to slide in sleeves 17. The" rear ends of rods 18 are rigidly connected to a platform 19. An electric motor 20 is also rigidly connected toplatform 19 as is a nut 21, the threads of which engagethe threads of an adjustment screw 22. Screw 22 is universally'coupled to a rod 23, the front end of which extends through a bushing 24 outside cabinet 11 where a handwheel 25 is affixed thereto. Motor 20 is provided with an armature shaft 26 which is keyed to a variable diameter driving pulley 27 mounted thereon for purposes of moving a V-belt 28 when motor 20 is energized. If handwheel 25 is moved so that nut 21 and thereby motor 20 are moved toward the rear of cabinet 11, belt 28 will separate the flanges of driving pulley 27 and reduce thev effective diameter thereof. Conversely, if handwh'eel 25 is rotated in the otherdirection, motor 20 will be moved nearer to post 14 and belt 28 will be driven at a higher speed for a given r.p.m. of motor 20 because of the greater eifective driving diameter of pulley 27. Thus, theparts just described constitute an adjustable speed construction for mechanism 10 to be run at whatever speed is selected for the turning of a rotor 29.

Rotor 29 in the illustrated embodiment being described is made of a non-yielding material like metal and the outer surface thereof is in the form of a single male helical thread with the cross section of the rotor at any point being circular. a drive shaft 30 on which, if desired, mixer blades 31 may be adjustably and detachably mounted for services where mixing, in addition to pumping, is wanted. A detachable coupling 32 has one portion connected to drive shaft 30 and the other portion connected, to a spindle 33. Such coupling 32 may be a flexible coupling by, for example, having one part made out of a somewhat yieldable material, if desired, and further, may be a coupling in which the parts are fastened together so that me lifting of spindle 33 will correspondingly lift shaft 30, thereby separating rotor 29 axially from a cooperating pling 32 upper and lower jaw parts thereof coupled for rotation byvirtue only of the fact that the upper part is resting l to 3 of the drawings, a new de- Rotor 29 is affixed to the lower end of fixed stator 34 to the desired distance, or couinthe illustrated embodiment may have the.

on the lower part under the force tending to move spindle 33 downwardly in a direction tending to keep substantially the entire length of rotor 29 within the length of stator 34.

Spindle 33 is rotatably but not axially movable in thrust bearings 35 which are fixed in place at the ends of a quill 36 having a rack portion 37 on the rear iace thereof. A collar 38 fixes the location of quill 36 along spindle 33, which spindle continues through and above collar 38 where it is provided with a splineway 39. A land 40 in the housing on frame 16 and a bushing 44 through which the splined portion of spindle 33 extends provide a guide for quill 36, in conjunction with an idler pinion 41 meshing with rack 37 to hold quill 36 slidably mounted for longitudinal movement without rotation of quill '36 relativeto frame 16.

A driven pulley 42 is rotated by belt 28 andis provided with a roller bearing 43 which is held against downward movement by bushing 44. A spline key connects pulley 42 to spindle 33 so that there can be no relative rotation therebetween although spindle 33 may move axially through driven pulley 42 from a lower extreme position illustratedin Figure 1 to an upper extreme position illustrated in Figure 2. There is an opening in top of cabinet 11 which is covered by a hood 46'into which the top of spindle 33 may project as occasion arises. If desired, a limit switch 47, shown in dotted outline, may be provided in machine in alignment with the axis of spindle 33 and electrically connected to motor 20 so that motor 20 is de-energized if and when spindle 33 should move into its extreme upper position shown in Figure 2. On the other hand, member 47 may have an alarm bell or light switch substituted therefor if desired.

An arcuate gear 48 is provided and meshes with idler pinion 41. Gear 48 is fixed to a gear shaft 49 mounted in bushings in the sides of frame 16, the gear shaft 49 projecting therebeyond and extending into a socket 50 at the from end of a lever 51. Lever 51 extends through an opening 52 in a counterweight 53 by means of which a predetermined force is selected and exerted upon gear 48 and therethrough upon rack 37, said force tending to move quill 36 and spindle 33 in a downward direction toward its lowermost position as shown in Figure l, the upper end of rack 37 and pinion 41 constituting a limit stop for any such downward movement. In that Figure 1 position of the new mechanism, the entire iength of rotor 29 is within and coincides substantially with the entire length of stator 34.

Counterweight 53 is provided with a further longi- .tudinal opening 54 extending .therethrough and having a female threaded portion for engagement by the threads of an adjustment screw 55. Screw 55 is connected by a universal coupling 56, intersecting the extended axis of shaft 49, toa rod 57 which is mounted at its front end in a bushing 58 and extends through the front of cabinet 11 where it is .afiixed to a handwheel 59. Hence, as handwheel 59 is turned in a direction which moves counterweight 53 to the rear, the force exerted by lever 51 upon gear 48 to move quill 36 in a downward direction is correspondingly increased, and vice versa.

Stator 34 is preferably made of a resilient material like neoprene or it may be made of some other'material, preferably of a pliable nature. On the other hand, stator 34 may also be made of a hard material provided there is a proper ratio between the helical threads on the respective rotor and stator. Rotor 29 comprises a single male helical thread as described above. The interior surface 60 of stator 34 compries, in the illustrated embodiment, two female helical thread portions, each of which has the same pitch circle at the pitch circle of the thread of rotor 29. Moreover, the two threads forming surface 60 are 180 angular degrees apart. Thus, the lead of the thread on rotor 29 is one-half the lead of either of the threads in stator 34.. The rotation of rotor 29, or of any thread turn thereof, in stator 34 will constitute a positive displacement pumping action and creating a pumping force which, by means of my new mechanism, will not exceed a predetermined limit.

In mechanism 10, the resilient stator 34 is encased in a cylindrical shell 61 having

flanges

62 and 63 for respective connect-ion to an outlet connection 64 of receptacle 13 and a discharge fitting 65. Material pumped by

pump elements

29 and 34 are forced through discharge fitting 65 into the continuing portion of the system of which mechanism 10 may be a part. However, if for any reason the pressure within fitting 65 rises to the selected limit determined by the setting of counterweight 53 along lever 51, rotor 29 will back out of stator 34 axially, without wholly leaving stator 34, a distance sufiicient to reduce the pumping force exerted by the rotation of rotor 29 to keep it within that selected limit without cessation of pumping. As soon as'the condition causing the pressure rise subsides, counterweight 53 will tend to return rotor 29 to its normal working position in stator 34 and, conversely, should the pumping force continue to rise, then rotor 29 will back farther away from the discharge end of stator 34 until a balance is reached at the preselected force limit, which may constitute an operating position between the extreme positions respectively represented in Figures 1 and 2. In the event that the reaction pressure effective adjacent the dischar e end 66 of rotor 29 continues to rise, rotor 29 may move into its extreme upward position shown in Figure 2 whereat it, in cooperation with stator 34, exerts very little pumping force while at the same time acting to .bar the return of material below end 66 into receptacle 13. As described above, an alarm or a limit switch 47 may be provided to stop all pumping when spindle 33 reaches the position shown in such Figure 2. It will be realized that different materials will require a idifiierent optimum setting of counterweight 53 and, also, that mixing equipment such as the paddles 31 will be wholly dispensed with in many services and, still further, that the embodiment shown in Figures 1 to 3 may take a variety of forms without departing from the principles illustrated by that construction.

In starting up rotor 29, the starting resistance may be readily overcome, if needed or desired, until the operation is fairly well started either by increasing the speed of the rotor through an appropriate turning of handwheel 25 or by reducing the initial pumping force by bringing counterweight 53 nearer to handwheel 59 by the turning of that handwheel 59 in an appropriate direction, following which when the operation is fully under way the speed of rotor 29 can be reduced to the normal operating speed if handwheel 25 had been moved, or handwheel 59 can be turned to increase the force setting of counterweight 53 to the predetermined limiting force selected for the operation so begun, respectively. It will'also be noted that the new mechanism of Figures 1 to 3 can be readily cleaned and sterilized and/or taken apart for maintenance servicing if and when desired. Such cleaning is of extreme importance in certain food and pharmaceutical processing fields. In the case of the embodiment being described, the spindle 33' may be moved toan upper position and the upper and lower parts of coupling 32 disengaged whereupon shaft 30 and rotor 29 may be readily taken away when receptacle 13, stator 34 and the pipes beginning with discharge outlet fitting 65 are cleaned. Similarly, the shaft 30, paddles 31 and rotor 29 can be cleaned before the device is reassembled to be ready for a new operation.

In the further embodiment illustrated in Figures 4 and 5, I have provided a device 70 which operates in accordance with my new principle disclosed in the mechanism of Figures 1 to 3. In device 70, a head member 71 of apump casing is provided with a port 72 to receive a flowable substance to be pumped out through a delivery member 73 having discharge outlet 74 therein, the outer end of delivery member 73 being closed by an end plate 75. A shell 76 extending between the members 7 1 and 73 completes the pump casing for device 70 on which legs 77 are provided for mounting in any desired position. A stator 78 preferably of resilient material and having a female thread character of the type described in connection with stator 34 is provided and joined to shell 76 so that there is no rotation of stator 7'8 as a rotor 79 rotates relative thereto to exert a pumping force operative upon the material entering port 72. Rotor 79 may also be constructed of a metal having its outer surface burnished, if desired, and with a single male helical thread as described in connection with rotor 29 with its lead distance per turn equal to one-half the lead of either of the two female threads which together comprise the internal surface 80 of stator 78. Rotor 79 is provided with a countersunk axial cylindrical recess 81 through which a connecting rod 82 extends. The forward end of connecting rod 82 extends through an opening 83 in the discharge end of rotor 79 and is provided with an eye which extends into a seal cap 84 which is joined thereto in articulated fashion by a pivot pin 85. Hence, as connecting rod 82 rotates, it will force rotor 79 to turn and as rotor-79 turns, it will wobble transversely in cooperation with the adjoining portions of surface 80 at the time being to provide the pumping force exerted by device 70.

The rear end of connecting rod 82 is provided with another ball eye which fits into a conical socket 86 in the forward end of a drive shaft 87. A rear pivot pin 88 pivotally connects the eye at the rear end of connecting rod 82 to drive shaft 87 at the apex of socket 86. Since the axis of rear pivot pin 88 is at right angles to the axis of front pivot pin 85', a universal connection is provided which will accommodate the transverse wobble or orbital movement of rotor 79 in the course of its being turned by shaft 87. A stuffing box 89 isprovided in the outer end wall of member 71 for the passage therethrough of shaft 87, with suitable packing being provided in the gland and a gland follower 90 holding the packing in place in the stuffing box and also bushing shaft 87. A separate antifriction hearing may be provided between follower 90 and shaft 87, if desired. It will be noted that no matter what the position may be in which device 70 is mounted, material pumped thereby will not come into contact with lubricated or other members of the device save those which are readily cleaned, and, if abrasive slurries, for example, are being pumped, the life of the packing in stuffing box 89 will be prolonged as will shaft 87 since the pumping force is exerted in a direction away from member 71 toward member 73.

A bearing casing 91 is provided in device 70 and is rigidly connected to head member 71 by brackets 92. Casing 91 may be rectangular in cross section and have a rectangular slide chamber 95 for a slidable roller thrust bearing unit 94. An opening 95 in the front wall of casing '91 and an opening 96 in a back cover 97 of casing 91 permit shaft 87 to extend therethrough as shown. The rear end 98 of shaft 87 is splined for slidable coupling to a prime mover such as an electric motor or other source of power to turn rotor 79 in the appropriate direction to develop pumping force for the discharge of material through port 74. Unit 94 is provided with a cylindrical interior surface 99 having roller thrust bearings 100 at the respective ends thereof separated by a spacer 101 and maintained in position relative to each other and to the unit 94. The inner races of bearings 100 engage a necked portion 102 of shaft 87, such shaft 87 having no axial movement relative to unit 94 by virtue of being secured between a shoulder 103 and lock nuts i104 engaging a threaded portion of necked portion 102.

A bracket stand 105 is rigidly affixed to the top of casing 91 to pivotally support a lever 106, the lower end of which extends downwardly through an opening 107' in casing 91 into a keeper opening 108 in the top of unit 94. Lever 106 is in the form of a bell crank having an outstanding arm 109 on adjustably secured by a set screw 111 so that a preselected force can be applied to lever 106 to urge unit 94 and thereby drive shaft 87 in a direction tending tomove rotor 79 into stator 78. In the position shown in Figure 4, rotor 79 has automatically and axially displaced itself rearwardly relative to stator 78 to stay within the pre-. selected force limit corresponding to the setting of counterweight 110, pursuant to the principle discussed hereinabove in connection with the embodiment set forth in Figures 1 to 3, such displacement correspondingly reduc:- ing the maximum pumping force achievable by cooperation of the

members

78 and 79 as when the respective lengths thereof are coincident. Thus, the device 70 is self-regulating in terms of the maximum force achievable by the pumping action exerted thereby, which maximum force is selective, as stated above, in accordance with the predetermined setting of counterweight 110.

A still further embodiment of my invention is illustrat ed in Figure 6, parts thereof corresponding generally in construction and functioning to parts shown in Figure 4 are provided with the same reference numerals with the addition of a prime accent thereto. In the still further embodiment of Figure 6 a motor 112 when energized drives drive shaft 87 through a flexible coupling 113 without, however and unlike'the case with drive shaft 87, any axial movement of drive shaft 87 being possible; In the still further embodiment of Figure 6, axial move-v ment or displacement of rotor 79 relative to stator 78' is otherwise provided for in that an axial bore 114 in rotor 79' is provided with splineways 115 engaged by corresponding projections on the sides of slidable cap 116. Splineways 115 are provided at the rear ends thereof with stops 117 to limit the rearmost position of cap 116 toward which rearmost position cap 116 is urged by a spring 118. The forward end of rotor 79' is provided with an internally threaded cylinder flange 119 at the front end of bore 114 in which a pair of threaded lock plugs 120are positioned at a preselected axial position therein to serve as a retainer for the forward end of spring 118. By adjustment of such lock plugs 120, the. force exerted by spring 118 is correspondingly adjusted. In operation, maximum pumping pressure of the Figure 6 embodiment, for a given number of revolutions per minute of the rotor, is achieved when flange 119 isin the dot-and-dash position illustrated in that figure. However, should the pressure rise in the pipe leading from port 74 so as to tend to exert a counterforce greater than the preselected limit, the rotor 79' will move toward the position illustrated in solid lines in Figure 6 to maintain the pumping force within the preset maximum established by the adjustment of spring 118. In this way, as in embodiments previously discussed, I have provided novel means for pressure relief which do not require discharge of pumped material outside the system or risk of rupture by pressure of one or more parts of a closed system in which such pumping is being done.

In Figure 7, I have shown yet another embodiment of my invention and parts thereof corresponding generally in construction and functioning to parts of the embodiment illustrated in Figure 6 are provided with the same reference numerals having however a double prime accent therewith. It will be seen that rotor 79" has an envelope which is generally in the form of the frustum of a cone with the portion of lesser diameter toward discharge member 73". Moreover, the envelope of interior surface of stator 78" correspondingly nar: rows. Accordingly, as and to the extent that wear oc-. curs, the normal position of motor 79" may be moved somewhat forwardly, that is, toward the smaller end thereof so as to 'take up such wear, such adjustment being performable either by appropriate adjustment movement of threaded lock plugs 120" or by the selec-. tion of another spring 118 to provide for such take-up,

which a counterweight is In addition, the embodiment illustrated in Figure 7 is provided with a further feature in the form of means to controllably vary the transverse section of the rotor space opening in stator 78". Thus, the crests 121 of one of the female helix thread portions comprising surface 80" have a helical passage radially outwardly thereof which is occupied by a' flexible tube 122 preferably vulcanized to the walls of such passage. A metal tube 123 of smaller diameter than the internal diameter of tube 122 is within such flexible tube 122 throughout its length within stator 78", such metal tube 123 having perforations along its length and around its circumference. The respective ends of perforated metal tube 123 are secured to

pipes

124 and 125 through appropriate fittings and a fluid such as water under an appropriate pressure is pumped through one of such pipes 124125, leaving the stator via the other, to fill tube 122 and press it radially outwardly to the desired pressure extent. The same provision in the embodiment of Figure 7 is provided for the other female helical thread portions 1210 in surface 80" as shown by the tube 122a and the perforated metal tube 123a therein, the respective connections thereto being marked 124a and 125a. In this way, the pressure within the

tubes

122 and 122a may be set at a lower figure during the initiation of a pumping action so that starting torque requirements of device 70" are relatively lower. There is no possibility of collapse of stator 78" because, for example, of the presence of perforated metal tubes 123 and 123a. As the operation gets fully under way, the fluid pressure within the tubes 122' and 122a can be increased to a normal operating figure for whatever greater preselected tightness of engagement contact between stator 78" and rotor 79" is desired for the particular operation. The

tubes

122 and 122a and the connections thereto may also be used to serve a cooling function for the circulation of a coolant fluid therethrough in the case of operations where such may be desired or useful.

Various modifications may be made in my invention and respective ones of the above described embodiments, without departing from the spirit of my' invention or the scope of the appended claims.

I claim:

1. In a self-regulating pumping mechanism, apparatus comprising, in combination, a resilient tubular stator having double lead helical female threads, a non-yielding rotor having its exterior surface comprising a single helical male thread, the pitch circles of said threads being generally equal and of uniform diameter, the lead of said stator threads being approximately twice the lead of said rotor thread, a driving shaft operatively connected to said rotor, a spindle detachably and flexibly coupled to said driving shaft, a quill rotatably supporting said spindle, said quill having a rack portion, a gear operatively connected to said rack, a housing in which said quill is mounted for longitudinal movement, a counterweight operatively connected to said gear to exert force upon said gear to bias said quill in the direction of urging said rotor into a position substantially wholly within said stator, means to shift the relative position of said counterweight to adjust the amount of force exerted by said counterweight upon said gear, and adjustable speed means operatively connected to said spindle to rotate said rotor at a preselected speed, whereby the development of a pumping force between said rotor and stator is limited by the force yieldingly exerted as a result of said counterweight so that said rotor will move axially relative to said stator in a direction opposite to said firstnamed direction to maintain said pumping force within said limit.

2. In a self-regulating pumping mechanism, apparatus comprising, in combination, a resilient stator having a longitudinal rotor opening with its interior surface comprising helical female thread portions, a rotor having its exterior surface comprising one less helical thread than said stator to cooperate with said interior surface of said stator to exert a pumping force, a driving shaft operatively connected to said rotor, a flexible connection between said spindle and rotor, a spindle detachably coupled to said driving shaft, a quill rotatably supporting said spindle, said quill having a rack portion, a gear operatively connected to said rack, a frame in which said quill is mounted for longitudinal movement, adjustable forceexerting means operatively connected to said gear to bias said quill yieldingly in the direction of moving said rotor farther into the rotor opening in said stator, and means operatively connected to said spindle to rotate it and thereby said rotor whereby the development of a pumping force between said rotor and stator is limited by the force yieldingly exerted by said first-named means.

3. In a self-regulating pumping mechanism, apparatus comprising, in combination, a stator member having a helically threaded rotor opening therethrough, a rotor member having its exterior surface helically threaded to pump in said rotor opening, said stator member having one more helical thread than said rotor member, one of said members being resilient relative to the other, the lead of said stator threads being approximately twice the lead of said rotor thread, a driving shaft operatively connected to said rotor adapted to be operatively connected to a prime mover, means operatively connected to said shaft to bias said shaft yieldingly in a direction to move said rotor generally axially into said rotor opening, and means to rotate said shaft.

4. In a self-regulating pumping mechanism, apparatus comprising, in combination, rotor and stator pumping elements having cooperating helically shaped threads, said stator element having one more thread lead than said rotor element with corresponding pitches on the threads of said elements respectively, one of said elements being pliable relative to the other, a cylindrical recess in said rotor, a connecting rod extending at least into said recess and having one end pivotally connected to said rotor forwardly of the rear end of said connecting rod, a drive shaft extending axially away from the rear end of said rotor, said connecting rod being pivotally connected to said shaft adjacent the end thereof nearer to said rotor, said pivots at said respective ends of said connecting rod being angularly displaced so as to be at right angles to one another for universal joint movement, a pump casing enclosing said rotor and stator elements, said shaft extending through one end of said pump casing, packing means to seal the opening for said shaft through said pump casing, a bearing casing, a slidable unit in said pump casing operatively connected to said shaft to permit said rotor to move axially relative to said stator, and adjustable means operatively connected to said slidable unit to bias said slidable unit to urge said rotor in a direction to bring the length of said rotor into general transverse correspondence with the length of said stator.

5. In a self-regulating pumping mechanism, apparatus comprising, in combination, rotor and stator pumping elements having cooperating helically shaped threads, said stator element having one more thread lead than said rotor element with corresponding pitches on the threads of said elements respectively, a connecting rod pivotally collected to said rotor element, a drive member positioned in generally axial relation to said rotor element, said connecting rod being pivotally connected to said drive member to provide a universal connection between said rotor element and said drive member, a pump casing enclosing said rotor and stator elements, a second casing, a slidable unit connected to said drive member in said second casing, and means operatively connected to said slidable unit to urge it toward said rotor element in a yieldable manner.

6. In a self-regulating pumping mechanism, apparatus comprising, in combination, rotor and stator pumping elements having cooperating helically shaped threads, said stator element having one more thread lead than said rotor element with corresponding pitches on the threads of said elements respectively, one of said elements being made of pliant material relative to the other of said elements, a drive member for said rotor element, a connecting member flexibly connected between said rotor element and said drive member, and means operatively connected to said rotor element to yield and move said rotor element away relative to said stator element to control the thrust force exerted by said rotor element.

7. In a self-regulating pumping mechanism, apparatus comprising, in combination, rotor and stator pumping elements having cooperating helically shaped threads, said rotor having one less thread lead than said stator with the pitches of said threads corresponding, at least one of said elements being made of a resilient material, a cylindrical bore in said rotor, splineways in said bore, a cap adapted to slide in said bore, said cap having projections engaging said splineways to enable said cap to move axially but not rotatably relative to said rotor, stops in said bore to mark one extremity of possible movement of said cap, a spring retainer in said bore spaced from said stops in an adjustable manner, a spring extending between said cap and said retainer, a connecting rod pivotally connected to said cap, a drive shaft extending axially away from one end of said rotor, said connecting rod being pivotally connected to said shaft in spaced relation to said cap, said pivots of said connecting rod being angularly spaced at right angles to one another for universal joint movement, a pump casing enclosing said rotor and stator elements, and means operatively connected to said shaft to rotate it to turn said rotor, whereby operating pressures in the discharge from said pump casing greater than the force exerted in accordance with the force produced by said spring will axially displace said rotor in a direction relative to said stator to reduce the pumping force which would otherwise be exerted by said rotor and stator pumping elements in a self-regulating pressure relief action.

8. In a self-regulating pumping mechanism, apparatus comprising, in combination, a rotor and a stator having cooperating helically shaped pumping threads, said rotor having one less thread lead than said stator with the pitches of said threads corresponding, a cylindrical bore in said rotor, a cap, means for moving said cap axially but not rotatably relative to said bore and rotor, a spring retainer in said bore spaced from said cap, a spring extending between said cap and said retainer, and a drive member flexibly connected to said cap whereby operating pressures in the discharge from said pump casing greater than t e orce e e e i ac o da ce i h t e shared of said spring will axially displace said rotor in a direction away from said stator.

9. In a self-regulating pumping mechanism, apparatus comprising, in combination, a stator member, said stator member having helically threaded interior surface portions forming a rotor member opening, a rotor member to cooperate with said stator member, said rotor memher having a helically threaded surface with one less helical thread than said stator member to cooperate with said interior surface of said stator member, the respective leads of said respective helical threads being in the ratio of the respective number of such threads on said stator and rotor members, means for normally maintaining said rotor member within said stator member to a predetermined extent, and yielding means operatively connected to one of said members to take up relative movement apart of said members to regulate to a predetermined maximum the pumping force developed between said members by relative axial rotation therebetween.

10. In a self-relieving pressure differential mechanism, apparatus comprising, in combination, a rotor member having a helically threaded surface, a stator member having an axially extending opening for said rotor member with the surface of said opening helically threaded in operative correspondence with the surface of said rotor, said rotor member having one less helical thread than said stator member with the pitches of said surfaces of said respective members corresponding, means operatively connected to one of said members to urged them into axially overlapping relation, said means further being yielding to move w'th said one of said members a sufficient distance at least as great as the axial length of one pitch upon the occurrence of a predetermined pressure in said device.

References Cited in the file of this patent UNITED STATES PATENTS Re. 24,079 Mateer Oct. 25, 1955 2,028,407 Moineau I an. 21, 1936 2,369,539 Delamere Feb. 13, 1945 2,532,145 Byram Nov. 28, 1950 2,545,626 Moineau Mar. 20, 1951 2,612,845 Byram et a1 Oct. 7, 1952 2,691,347 Zimmer Oct. 12, 1954 2,733,854 Chang Feb. 7, 1956 2,765,114 Chang Oct. 2, 1956 2,778,313 Hill Jan. 22, 1957 FOREIGN PATENTS 473,930 Canada May 29, 1951 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2.957 427 October 25, 1960 I Walter J. O'Connor It is h'ereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read'as corrected below Column 1,

lines

30 and 31, for "viscose" read viscous column 3, line 39, for "frone" read front line 71, for "at" read as column 5, line 54, for "95" ead 93 column 8, lines A and 5, strike out "a spindle detachably coupled to said driving shaft," and insert thesame after "rotor in line 3, same column 8; same column 8, line 6.2

for "collected" read connected column 10 line 29, for "urged" read urge same column 10, line 44, list of 1 references cited under UNITED STATES PATENTS, for "Zimmer" read Signed and sealed this 6th day of June 1961 (SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents